Method of corrugating tubing



y 1954 s. R. CARSON 83,928

METHOD OF CORRUGATING TUBING Filed Sept. 12, 1950 Q STANLEYECAESM/ a1, .9 Wii 5%;

H/s HTTOB'NEYS Fatented July 20, 1954 METHOD OF CORRUGATING TUBING Stanley E. Carson, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application September 12, 1950, Serial No. 184,417

4 Claims.

1 This invention relates to a method of forming integral peripheral beads or flanges on the surface of metal tubes of round or near-round cross section and having walls of substantial 2 an enlarged scale, illustrating progressive flowing of the metal while forming the beads according to this invention by endwise compression of the ground tube. More specifically, Fig. 4

thickness, the method being usable either in the 5 shows the grooved tube and compression ring manufacture of beaded or flanged tubing for assembled upon an interior mandrel, before the sale as such, or as a step in the manufacture of endwise compressing force is applied; Fig. 5 other articles including such beaded or flanged shows the metal of the tube between two adjatubing as a part thereof. cent grooves beginning to flow and bulge out- An object of this invention is to provide a very wardly away from the interior mandrel; and Fig. simple and economical method of forming such 6 illustrates the final formation of one bead. integral beads or flanges by first forming pairs of Fig. 7 is a section on line 7-? of Fig. 6. small peripheral grooves in the outer surface of Figs. 8 and 9 show an application of the method a plain metal tube and then compressing the tube of this invention in making a joint unit comprisendwise with a snugly fitting mandrel therein ing a corrugated or beaded inner tube and an to cause the metal thereof to flow outwardly and outer retaining shell having a resilient rubber form substantially uniform section solid periphbushing held permanently compressed therebeeral beads or flanges on said metal tube. tween. Fig. 8 illustrates the assembly prior to Another object is simultaneously to provide a compressing the inner tube endwise to form the series of such beads or flanges spaced along the corrugations or beads therein. Fig. 9 shows a length of the metal tube by a single endwise comlongitudinal section thru the final joint unit. pression operation on said tube, the location, sec- In the specification wherein similar reference tional shape and size of said beads being predecharacters refer to similar parts throughout the termined by the location, shape and spacing of several views, I have illustrated my novel process the pairs of grooves formed in said tube. as applied to a piece of steel tubing 18, seamless Another object is to provide a method of using or welded, 3 inches long, five-eighths inches my invention in assembling an article such as O. D. and having a wall thickness or" approxia bushing of resilient rubber or other resilient mately one-sixteenth inch. Four pairs of narmaterial compressed between an inner metal tube row grooves ii are cut therein as shown in Fig. beaded or flanged according to my novel method, 3. Each pair of grooves II are spaced closer and an outer retaining shell whereby the retogether than the spacing between adjacent pairs silient bushing is permanently secured in place of grooves. In Fig. 3 the center lines of the under compression. Such units may be used as grooves of each pair ll are spaced one quarter cushioning mountings and oscillating pivot joints inch apart while the next adjacent center line wherein the relative movement between the inner is spaced one-half inch. The width of grooves metal tube and the retaining shell is taken by H is approximately three sixty-fourths inch and internal distortion of the resilient bushing and said grooves are approximately half round in Without any relative sliding movement between cross section and preferably have a depth of from the parts. one-fourth to one half the wall thickness of tube Other objects and advantages of the present it! (see Fig. 4). invention will be apparent from the following Tube it is slipped upon a snugly fitting indescription, reference being had to the accomterior mandrel [5 which prevents otherwise pospanying drawings wherein a preferred embodisible radially inward bulging or flow of the metal ment of the present invention is clearly shown. of the walls of tube it when it is subjected to In the drawings: high endwise compression. Fig. 4 shows how Fig. 1 is a side View of a metal tube having four tube it may be subjected to a high endwise cornperipheral beads thereon made according to this pressing force (indicated by arrow A) which acts invention. thru the compression sleeve it which telescopes Fig. 2 is a longitudinal section thru the tube upon the projecting end of mandrel It. The opof Fig. 1. posite end of tube It is of course supported by Fig, 3 is id ie of the met l tube, h va suitable stationary abutment which reacts ing four pairs of spaced peripheral grooves thereagainst the compressing force A. The assembly in, as used in making the beaded tube of Figs. 1 shown in Fig. 4 may be inserted between the and 2. platens of a hydraulic press to obtain the end- Fiss. 4, 5 and 6 are partial sectional views, on wise compressing iorceAby forcing sleeve it endfitting mandrel, then compressing said tube endwise and causing the metal thereof between each pair of said grooves to bulge and flow outwardly into the adjacent space unconfined by any shaping member and form substantially solid outer peripheral flanges on said tube while the portions of said tube between the flanges thus formed retain substantially the original tubular dimensions.

4. The method of permanently assembling a bushing of resilient material compressed between an inner metal tube and an outer retaining shell which includes the steps of forming a plurality of spaced pairs of exterior peripheral grooves on the inner metal tube so as to reduce the thickness of the tube at the groove, sliding said grooved inner tube endwise thru a closely fitting bushing of resilient material and assembling said bushing and grooved tube inside of an outer retaining shell, passing a snugly fitting mandrel within said grooved tube, then compressing said grooved tube endwise with such a force as to cause the metal thereof between each pair of said grooves to bulge outwardly and form radial flanges projecting into the material of said resilient bushing and thereby compressing the material of said bushing.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,095,100 Fulton Apr. 28, 1914 1,270,402 Fulton June 25, 1918 1,288,132 Nagle Dec. 17, 1918 1,734,025 Zeibig Oct. 29, 1929 1,734,932 Weed Nov. 5, 1929 1,961,453 Quarnstrom June 5, 1934 2,118,499 Durbin May 24, 1938 

